Despite ongoing innovation in this field, the provision of detergents with bleach remains a technically difficult endeavour. Bleaches are desirable for their stain-removing, dingy cleanup, whitening and sanitization properties; yet there are some frequently encountered disadvantages of effective bleaches. These include color damage on fabrics and damage to laundry appliances, especially the rubber hoses these appliances may contain. The most common bleaches are oxidants and are often difficult to coformulate with the current, improved but still oxidation-prone enzymes and other detergent ingredients. Moreover the legislated removal of phosphate builders from detergents in some geographies makes it necessary to develop bleaches which operate effectively in the presence of nonphosphate builders which can be bleach-sensitive or may leave relatively high levels of calcium and magnesium in the water as compared to fully phosphated builder systems.
Modem bleaches for detergents include those comprising a hydrogen peroxide source, such as sodium perborate, and a bleach activator. The term "bleach activator" as used in the art refers to a compound which reacts with hydrogen peroxide or its anion to form a more effective oxidant. Known bleach activators include perhydrolyzable acyl compounds having a leaving group such as oxybenzenesulfonate. Detergents in the market today moreover include those in which the relatively mild and enzyme-compatible hydrogen peroxide source is combined with detersive enzymes; optionally with tetraacetylethylenediamine (TAED) or nonanoyloxybenzenesulfonate (NOBS) as bleach activators. It would be desirable to further improve these detergents, for example, by adding additional bleach activator types which extend the variety of stains removed. Achieving such improvement however brings with it a high risk of potential adverse effects, such as those noted supra. Numerous bleach activators may have other deficiencies, such as low enzyme compatibility, limited storage stability, low mass efficiency, surfactant incompatibility, tendencies to produce malodorous peracids, synthesis difficulty, lack of biodegradability, and high cost. These factors perhaps account for the observation that although strenuous efforts have been made to improve the efficacy of bleach activators and hundreds of such activators have been described in the literature, only TAED and NOBS have been widely successful.
The disclosure of many bleach activators in the context of laundry formulations includes the suggestion that quaternary substituted versions of such activators may indeed be of a depositing nature and, in consequence, have desirable fabric conditioning properties. See, for example, U.S. Pat. No. 4,751,015 at col. 3, lines 22-27. This patent as well as EP 427,224 and EP 408,131 are also illustrative of disclosures of bleach activators which may include chemical groups which may be cationic and/or which may form peroxycarbonic acids when perhydrolyzed.
Among the many efforts which have been made to improve bleach activators for laundry purposes, it has also been disclosed that diperacids can have beneficial effects. See, for example, Kirk Othmer's Encyclopedia of Chemical Technology, 4th. Ed., 1992, John Wiley & Sons, Vol. 4, ppg. 271-300, "Bleaching Agents (Survey)" which includes reference to diperoxydodecanedioic acid (DPDA) and its homologs. Such compounds have the formula HOOC(O)(CH.sub.2).sub.n C(O)OOH wherein n is typically 10 but can in general range more widely. Although the peroxy moieties of the diperacid are ionizable and hydrophilic, such diperacids contain in addition only a non-hydrophilic aliphatic "spacer", --(CH.sub.2)n--, separating the two peracid moieties. In short, they do not contain peroxide-free hydrophiles of the types and substitution positions described hereinafter. By way of additional diperacid disclosures, EP 68,547 describes aromatic diperoxyacids. U.S. Pat. No. 5,071,584, U.S. Pat. No. 5,041,546 and EP 316,809 describe heterocyclic polypercarboxylic acids and/or salts of amino-polypercarboxylic acids. As in the case of DPDA, such compounds lack a strongly hydrophilic moiety situated in-between the peracid moleties.
These improvements notwithstanding, there is no widely commercialized laundry detergent comprising a cationic or diperacid-forming bleach activator.
It is accordingly an object herein to provide improved detergent compositions and hard surface cleaners comprising particularly selected bleach activators, formulated to deliver superior cleaning and stain removal while reducing color fading and other deficiencies of art-disclosed detergent compositions which rely on cationic bleach activators.